


Don't Forget

by StardustFandoms



Category: Undertale (Video Game)
Genre: Fluff and Angst, Gaster is a nerd, Gen, How Do I Tag, Ketchup Addiction, Mostly fluffy but a helping of angst on the side, Parent W. D. Gaster, Sans has a vision of the future, They're both nerds, but he doesn't know it, nightmare fic, sans is a nerd
Language: English
Status: In-Progress
Published: 2020-02-17
Updated: 2020-02-17
Packaged: 2021-02-18 22:36:45
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,793
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22767622
Author URL: https://archiveofourown.org/users/StardustFandoms/pseuds/StardustFandoms
Summary: Sans has a nightmare and Dadster comforts him.
Relationships: W. D. Gaster & Sans
Kudos: 31





	Don't Forget

Dark. Darker. Yet, darker. The darkness keeps growing all around him, the shadows cutting deeper. Sans walked across the expanse. In the distance, he saw something bright. Upon closer inspection, he realized it was a golden room. He stepped into it and looked around. The walls and pillars shone golden with the light of outside. There weren’t e pretty stained-glass panes that made the room twinkle even brighter. A short figure stood in the shadow of a pillar. Sans began to approach them when the figure stepped forward. The small skeleton gasped when he saw who it was. It was...him. A much older version of him, but nonetheless still him. His smile looked strained. Something was wrong. He seemed to be glaring at something behind him. When he stared back, he saw a human. Sans immediately took a step back. However, this human was different from the one that plagues him. They were wearing a blue shirt instead of an orange one. Their hair was brown instead of blonde, and they weren’t wearing a bandana. This one. This one seemed almost innocent. If it weren't for the bloody knife in their hand and the layer of dust covering their body, Sans might have believed it. But this one seemed more murderous than the one at the lab that day. Suddenly, his other spoke. 

“It’s a beautiful day outside. Birds are chirping. Flowers are blooming. On days like these, kids like you should be burning in hell.” 

In a flurry of attacks, the older Sans attacked. First with blue magic, then with the prototype weapons his father was working on. The human attacked as well, but the Sans avoided every single one. Sans watched helplessly from a corner as the battle dragged on, his counterpart getting more and more tired with every turn. Eventually, the older Sans fell asleep. And the human attacked. Sans screamed as his other fell to the floor, grasping his bleeding wound. He tried to walk away. Then he disappeared into dust. Sans tried to run forward, but then the darkness enveloped him once more. He turned around, hyperventilating, to try to find a way back. He needed to stop the human before-. Sans saw the familiar shape of his father standing near another room. He ran forward and enveloped him in a hug, tears staining his pristine white lab coat. Gaster didn’t acknowledge this, instead he just watched. 

This room was much more familiar. It was their house in Snowdin. In fact, Sans remembered this very scene. It had happened last week. Gaster was on the couch, feeding Papyrus, while Sans lay doodling in front of them. He drew his dad, his brother, and then himself. Sans jumped up to show his dad his creation. Gaster chuckled and asked if he could keep it for the lab. Sans had happily obliged, and the next day Gaster had appeared with a frame. The scene suddenly glitched out and disappeared into the darkness. His father too, seemed to have disappeared. However, when Sans took a step back to look at his face. He realized that this Gaster was horribly deformed. His eyes and seemingly eternal smile appeared to be melting right off his face. His eye lights were burning brightly with pure insanity. His body was the same color as their surroundings. Pure, utter darkness. A void inside a void. It seemed like it had consumed him, eaten away at him until all that was left was the empty husk of the person he used to be. Sans began to shake, and he tried to take a step back. However, the creature that used to be his father grabbed Sans with two disfigured hands and leaned down to be face-to-face. 

“Don’t forget”. 

Then he woke up with a gasp. The skeleton was drenched in sweat and was breathing heavily. It took Sans a minute to register his surroundings. A soft snoring noise came from beside him and he realized that a hand was draped around his midsection. He was in bed. It had just been a nightmare. A terrible, hyper-realistic nightmare, but still just a nightmare. He was safe in bed with his dad, who was still his geeky self, and not some sort of insane void creature. Papyrus’s soft breaths could be heard as well. His crib was right next to the bed, so Gaster could easily check up on him during the night. Everything was ok. There was nothing to worry about. However, Sans still couldn’t sleep, which was a hard thing to believe considering the skeleton was one who could fall asleep anywhere anytime. When the skeleton closed his eyes all he could see was the mangled face of his father or the way the blood on a knife dripped down onto golden floors. Sans cuddled closer into his father’s embrace. Instinctively, Gaster pulled him closer. Sans’ soul felt warmer and began to glow softly. Finally, he allowed himself to relax. But still, he could not sleep. 

Sans weighed his options. He could either stay there and see if sleep came on their own, wake his dad up, or sneak out of his grasp and go to the kitchen for a midnight snack. Speaking of midnight, Sans checked the time. The clock on their bedside table read 4:30am. Which meant he had to wake up for school in about 3 hours. Sans mentally groaned. He was definitely going to fall asleep in Mrs.Doggers class. 

Eventually, Sans decided that the second option was out of the question. Taking care of a babybones was hard work. Papy had their father running up and down all day and night. By the time Gaster hit the hay, he was already sound asleep. Sans was actually pretty surprised that Papyrus had managed to sleep for so long. He usually wakes up at about 3am begging for food. Anyways, it wouldn’t be right of him to wake his exhausted father just because of a stupid nightmare. 

Sans decided that he would try the first option and leave the second as a last-minute resort. Sans closed his eyes and tried counting backwards from 10. 

10...a flash of blue. 

9...a glinting knife. 

8...red against white. 

7...dust scattering. 

6...a rumpled lab coat. 

5... three badly drawn figures. 

4... 

“d-ontt fOforgeet.” 

Sans opened his eyes wide and gasped. The skeleton next to him felt his movement and stirred gently in his sleep. He tried to regulate his breathing as to not disturb Gaster more. When Sans was sure that his father was unlikely to wake up, he slowly moved out of Gaster’s embrace and tip-toed out of the room. Once downstairs and in the kitchen, he opened the cupboard that contained his not-so-secret ketchup stash. Due to Sans’ mild addiction to ketchup, Gaster usually allowed him 2 cups a day. However, when Sans felt the need for more, he would sneak bottles from Grillby’s. He had made the fire monster pinky promise he wouldn’t tell his father about it. He had reluctantly agreed, only on the condition that he pay him back later. As if that would ever happen, Sans thought to himself. He picked the biggest bottle, an industrial sized gallon he got as a reward for helping Grillby prank his father. Sans snickered just thinking about it. They had replaced all of Gaster’s chemicals with condiments. Needless to say, when Gaster mixed what he thought was calcium hydroxide and water, the result was a bit...explosive. Sans got grounded for about a week after that, but every second of it was worth it. 

Sans took a swig of the bottle and relished in its tangy flavor. He glanced at the clock that hung over the stove. It read 5:30. An hour and thirty minutes left until school. The small skeleton sighed and made his way over to the reading chair. He sat down with a soft thud and took another gulp of ketchup. Sans figured he would make a case to Gaster about skipping school, but he had already missed 3 days a month ago due to Papyrus’ arrival, so it was unlikely the older skeleton would let him. Which meant that he would have to endure a 6-hour school day with 6 hours of sleep. Sans had no problem snoozing in most of his classes. In fact, he did just that. At first, his teachers complained to his father. However, Gaster just quoted Sans’ low HP and how his grades were above average, so the teachers could do nothing but helplessly watch as slept through their lectures. 

However, when it came to Mrs.Doggers, it was a whole different story. In his math and science classes, Sans excelled because his father was the royal scientist. He worked in the lab along with him, learning hands on. In history, Gaster knew a fair amount, considering he grew up on the surface. But Mrs.Doggers taught Language Arts. Sans did not like Language Arts. Sans did like reading, but he liked reading about things such as quantum physics or astronomy. He did not like reading about fluffy bunnies and delusional chickens who think the sky is falling, although the chicken one was kind of funny, he had to admit. The problem was that since he did not like it, he did not do good in said class. And that did not stand well with Gaster. So, his father gave him an ultimatum; if he did not get his grade up to at least a B in the next 2 weeks, he would lose his lab privileges until he raised them. 

Now, there were few things Sans cared for, such as puns, ketchup, sleep, and more puns. But the lab, the lab was special. During the weekends, Sans and Gaster would spend all their time there, experimenting together and learning from one another. During the week, Sans hardly had any time to spend with his father, between homeworks and blueprints they could hardly eat dinner together, relying mostly on Grillby. But in the lab, both of them were free. Sans felt complete. And he would not lose this over some stupid spelling tests. He took another swig of ketchup in frustration. 

“Sans?” 

Sans yelped and jumped in his seat. He turned his head to find Gaster towering over him in his pink fluffy robe, eyelights dim in grogginess and glasses slightly crooked. 

“Hiya dad, uh, good morning?” 

Gaster blinked down at him, still trying to fully wake up. 

“What are you doing up so early?” He asked, taking the half-empty bottle of ketchup from Sans’ hands and placing it on the coffee table. 

Sans grumbled in response to the loss of his beloved ketchup. “What time is it, anyways?” 

“It’s 6:30, why? How long have you been up? Why didn’t you wake me?” 

Sans buried his head in hands and groaned. How had it been an hour already? There was no point in going back to bed now, he supposed. Suddenly a pair of arms lifted him into the air. Gaster sat down in the chair and plopped Sans in his lap. Sans wasted no time in cuddling close into him. 

“Now, tell me what happened.” 

Sans gulped, not wanting to relive the memory. 

“I-I had a nightmare...” 

Sans felt Gaster instinctively wrap his arms tighter around him in a protective gesture. 

“Was it the human again?” Gaster said slowly. 

“W-well there wa-s a h-uman bu-but they, it wasn’t him.” Sans stammered, body trembling slightly. 

Gaster hummed in understanding and ran a hand against his spine soothingly. Sans relaxed into his touch and closed his eyes. 

“You don’t have to tell me if you aren't comfortable, y’know” Gaster finally said after a while. 

“I want to.” Sans said, taking a deep breath. 

“I was in a dark place, kind of like a void. And in the distance, I saw a room and I walked towards it. When I stepped into it, I saw myself, but it wasn’t really myself. It was an older me, and he looked angry. When I turned around, I saw a human, but it was a different human. They had a blue jacket and they were holding a knife. A very, bloody knife. And I was so scared. Then they started to fight and the older me was winning until he fell asleep. Then, then-” Sans choked down a sob. He balled his fists in the fabric of Gaster’s robe. 

“Th-they...THEY KILLED ME DAD!” Sans finally said, bursting out in tears 

Gaster pressed the little skeleton closer into him. Sans buried his head in the crook of Gaster’s neck as he cried. 

“I-I had to watch as I bled out and got dusted.” 

“Shhhh, my child. It was just a nightmare. I promise that, as long as I live, I will protect you against anyone or anything that tries to hurt you or your brother. You two are the most important thing in my life, and don’t you ever forget that.” 

Sans chuckled a bit through his tears. “Even more than science?” 

Gaster smiled, “Even more than science.” 

“Aw shucks, old man, that means a lot.” Sans said through a grin. 

“I told you not to call me that.” 

“Whatever, Old man.” Sans teased even further. 

“Alright, that’s it. It’s time for a visit from the tickle monster!” Gaster said as he ran his hands up and down Sans’ ribs, causing him to squeal and jump down onto the floor. Gaster followed and pinned the smaller skeleton to the ground. 

“Who’s an ‘old man’ now?” 

“Y-you still are!” Sans managed to say in between fits of giggles. 

“Oh yeah?” Gaster said through a smirk as he began another tickle attack. 

“Nooooooo sttaaaappp daad pleaasee” 

“Am I still old?” 

“Yeeessss” 

“Alright then, I guess more convincing is an order...” 

“OKAY, OKAY I GIVE YOU AREN’T OLD” 

“Are you gonna call me old again?” 

“Noooo, I wonttt” 

“Good.” 

Gaster sat up and grabbed his glasses from where they had fallen in their little scuffle. Sans rubbed at his ribs and chuckled. 

“Welp, I’m going to make some tea then go check on your brother. You want some? 

“You mean Papyrus or tea?” 

Gaster tutted as he picked up the gallon of ketchup and carried it to the kitchen. “I can’t be-leaf you would ask that, Sans”. 

Sans snickered. “Chamomile”. 

“Remember your manners, son” Gaster said as he turned the stove on and prepared the kettle. 

“May I please have a cup of chamomile tea, your royal highness?” 

“Hmph, I can't believe I'm raising such a disrespectful child”. Gaster added the teabag to the water and sat down on the couch next to his son. 

“Hey, what can I say, dadster, I guess manners just aren’t my cup of tea”. 

Gaster grinned and gave the smaller skeleton a playful shove to the elbow. 

“Y’know you’re a nerd, right?” 

“So are you”. 

“Yup, we’re both nerds, aren’t we?” Sans said as he cuddled into his dad’s side. 

They stayed there for quite a bit of time, just relishing in the company of one another. Sans debated whether to tell him the second part of his dream or not. He really didn’t want to get upset again. But, he felt like if he told Gaster now, he could maybe find some closure to the whole ordeal. 

“Dad I-” 

The kettle of tea in the kitchen began to steam. Gaster excused himself and came back with two steaming mugs of chamomile tea. The sweet aroma of the tea was already enough to calm Sans’ frazzled nerves. He took a sip of it, enjoying its taste before it dissolved in his mouth. 

“Sans, were you about to say something?” Gaster asked before taking a sip of his tea. 

“Yeah, um, remember my nightmare? That wasn’t the only part...” 

“Sans are you sure you want to-” Gaster began but was cut short. 

“Yes, I'm sure, dad. Maybe I will finally be able to fall asleep if I do”. 

Sans took a deep breath and began. 

“After the other me, um, died, I ran towards but then the room disappeared, and I was back in the void. I turned around, and I saw you in front of another room, which turned out to be our living room. And I saw last Sunday, when I made that drawing for you. I hugged you, and then when the memory ended and the room disappeared you did too, kind of. In your place was a creature with a horribly disfigured face and he was so scary. He looked kind of like you, but he wasn’t I could tell. Then, he said, ‘Don’t forget’ and I woke up”. 

Gaster looked thoughtful for a moment, before speaking.

**Author's Note:**

> THIS WILL BE FINISHED I SWEAR I JUST LOST THE OTHER HALF OF THE STORY AND I CANT FIND IT BUT I WILL REWRITE IF I HAVE TO!


End file.
